Hello,
I find this Alti3D layer could be quite useful mapping path under tree cover or in remote areas.
Exemple :
https://map.geo.admin.ch/mobile.html?lang=en&topic=ech&bgLayer=ch.swisstopo.pixelkarte-farbe&layers=ch.swisstopo.zeitreihen,ch.bfs.gebaeude_wohnungs_register,ch.bav.haltestellen-oev,ch.swisstopo.swisstlm3d-wanderwege,ch.astra.wanderland-sperrungen_umleitungen,ch.swisstopo.digitales-hoehenmodell_25_reliefschattierung,ch.swisstopo.swisssurface3d-raster.metadata,ch.swisstopo.swissalti3d-reliefschattierung_monodirektional,ch.swisstopo.swissalti3d-reliefschattierung&layers_opacity=1,1,1,0.8,0.8,1,0.75,1,1&layers_visibility=false,false,false,false,false,false,false,false,true&layers_timestamp=18641231,,,,,,,,&E=2527078.16&N=1175481.89&zoom=10.414259949084514&catalogNodes=457,508

However it is not clear to me if this can be used for OSM mapping.
https://www.geocat.ch/geonetwork/srv/eng/md.viewer#/full_view/1964cc81-5298-460f-9228-41120315bea8/tab/complete

Any advice appreciated.
Regards,
Yves